I use Tetra brand algae wafers, and they work just fine for me. If they don’t eat it, you can try to blanch some cucumbers or zucchini’s. When I first got my snails, they wouldn’t eat anything except vegetables. After a while, I weened them off of veggies, and onto wafers. If they don’t eat either, they’ll eventually either 1(. Die of starvation or 2(
. Learn to eat what you provide. (Don’t take #1 seriously, just a joke.
) Good luck!
As to the OP, mine do that all the time. Same thing with my Blue Rams Horn Snails. My pleco has sort of a hang out spot and I chuck one down there for him to nibble on and a few minutes later, over 60 snails are on that one wafer. It just takes time and experience to learn how quickly the snails will get there, and what time of day to him your pleco.